Record UMA when googlezip proxies are removed from the proxy config.

chrome/browser/net/pref_proxy_config_tracker_impl.h

Index: chrome/browser/net/pref_proxy_config_tracker_impl.h
diff --git a/chrome/browser/net/pref_proxy_config_tracker_impl.h b/chrome/browser/net/pref_proxy_config_tracker_impl.h
index f09cfef3b799fcf47ae864080232963f55958eec..a98b37d30a00fb672351c19fec626300c595cf2d 100644
--- a/chrome/browser/net/pref_proxy_config_tracker_impl.h
+++ b/chrome/browser/net/pref_proxy_config_tracker_impl.h
@@ -81,6 +81,16 @@ class ChromeProxyConfigService
 // ChromeProxyConfigService::UpdateProxyConfig to use.
 class PrefProxyConfigTrackerImpl : public PrefProxyConfigTracker {
  public:
+  // Enum values that can be reported for the
+  // Net.PrefProxyConfig.GooglezipProxyRemovalResult histogram. These values
+  // must be kept in sync with their counterparts in histograms.xml. Visible
+  // here for testing purposes.
+  enum GooglezipProxyRemovalResult {
+    GOOGLEZIP_PROXY_REMOVAL_RESULT_NOT_FOUND = 0,
+    GOOGLEZIP_PROXY_REMOVAL_RESULT_FOUND_AND_REMOVED,
+    GOOGLEZIP_PROXY_REMOVAL_RESULT_MAX
+  };
+
   explicit PrefProxyConfigTrackerImpl(PrefService* pref_service);
   ~PrefProxyConfigTrackerImpl() override;